This application claims the priority of German Patent Application Serial No. 199 48 108.3, filed Sep. 27, 1999, the subject matter of which is incorporated herein by reference.
The present invention relates to a device for aiding a movement of a current collector trolley in and out of an elongate plastic profile of a sliding contact line.
According to company brochures, entitled xe2x80x9cSicherheits-Schleifleitungen in Kunststoffxe2x80x9d [safety sliding contact lines of plastic] and released by Paul Vahle GmbH and Co.KG (catalog nos: 4c/D96 and 4a/D91), current collector trolleys are described which are intended to move in and out of an elongate plastic profile of a sliding contact line which accommodates longitudinally therein current conductor rails. Funnels are used as guidance during in-and-out travel of the trolleys. Typically, the funnel is held in alignment with the plastic profile by a sleeve such that the rear end of the funnel is positioned in end-to-end relationship with the confronting end of the plastic profile whereby the sleeve laps over the end of the plastic profile.
The attachment of the funnel to the plastic profile in this conventional manner is disadvantageous because a protection against accidental contacting cannot be ensured, or can only be ensured in a complicated manner. In particular, the provision of a sufficient protection against accidental contacting rules out a compact design of the funnel. Moreover, there is no assurance that the creeping distance has a sufficient minimum length to comply with safety regulations, without complex mechanical finishing works. Another drawback of this conventional device is the complexity of assembling many single components.
It is thus an object of the present invention to provide an improved device for aiding a movement of a current collector trolley in and out of an elongate plastic profile of a sliding contact line, obviating the afore-stated drawbacks.
This object, and others which will become apparent hereinafter, are attained in accordance with the present invention by providing a funnel, and a sleeve embracing in a form-fitting manner the elongate plastic profile of the sliding contact line and intended to secure a rear end of the funnel to one end of the plastic profile, whereby the sleeve is freely movable along the plastic profile before securement of the funnel and laps over the end of the plastic profile when the funnel is secured in place, wherein the rear end of the funnel has a contour complementing an inner contour of the plastic profile and is received in form-fitting engagement in the elongate plastic profile.
In accordance with the present invention, the funnel projects into the elongate plastic profile such that the sleeve embraces the elongate plastic profile and the funnel in a form-fitting manner. As a consequence, the device is compact in structure and ensures sufficiently long creep distance while also realizing a sufficient protection against accidental contact. Through provision of the sleeve, an interlocking assembly of the funnel, the sleeve and the elongate plastic profile is obtained in a simple manner, i.e. plastic parts overlap one another. As a consequence, a short overall length of the device is realized so that tools for injection-molding these plastic components can have a simplified design. Moreover, there is no need to re-finish the end of the elongate plastic profile.
Suitably, the rear end of the funnel is at least partially tapered so that the funnel is easier to insert into the confronting end of the elongate plastic profile.
According to another feature of the present invention, the funnel snaps in the sleeve to realize a rapid and secure locked connection between the funnel and the sleeve. Suitably, the sleeve is secured to the elongate plastic profile by screw fasteners.
In order to maintain a short funnel design while still designing the funnel long enough for insertion in the elongate plastic profile, the funnel is provided with electrically insulating spacer elements extending rearwardly out from the funnel into the elongate plastic profile and connectable to the conductor rails in one-to-one correspondence. Suitably, spacer elements can be interconnected in a form-fitting manner to modify the overall length of insertion by which the funnel projects into the elongate plastic profile. In this way, a single spacer element length ensures different depths of insertion of the funnel in the elongate plastic profile. A simple construction is realized when the spacer elements are connectable in form-fitting manner with the rear end of the funnel.
Installation can be further simplified by inserting the spacer elements in the elongate plastic profile in anchoring grooves that are also provided for receiving the conductor rails. In this manner, the conductor rails projecting out from the elongate plastic profile can be connected with the spacer elements before installation, and the spacer elements can then be connected to the funnel. After this pre-assembly, the spacer elements together with the conductor rails and the funnel can be pushed into the elongate plastic profile.
According to another feature of the present invention, the spacer elements have one inwardly directed side which is formed with at least one vertical groove that extends transversely to the longitudinal axis. Thus, abrasion marks by the carbon brushes of the current collector trolley can be avoided. The groove thus prevents in a simple manner the formation of a continuous abrasion mark so that the insulating properties of the spacer elements are maintained even after an extended operation of the sliding contact line.
Through the provision of a device according to the present invention, it is assured in a simple manner that the neutral conductor is always contacted first, even at an asymmetrical operation of the device. It also permits an easy solution to fabricate funnels as mirror images from one another, i.e. a right and left configuration for attachment of funnels on opposite ends (entry funnel or exit funnel).